Statistical Modeling with a Hidden Markov Tree and High-resolution Interpolation for Spaceborne Radar Reflectivity in the Wavelet Domain

With the increasing availability of precipitation radar data from space,enhancement of the resolution of spaceborne precipitation observations is important,particularly for hazard prediction and climate modeling at local scales relevant to extreme precipitation intensities and gradients.In this paper,the statistical characteristics of radar precipitation reflectivity data are studied and modeled using a hidden Markov tree(HMT)in the wavelet domain.Then,a high-resolution interpolation algorithm is proposed for spaceborne radar reflectivity using the HMT model as prior information.Owing to the small and transient storm elements embedded in the larger and slowly varying elements,the radar precipitation data exhibit distinct multiscale statistical properties,including a non-Gaussian structure and scale-to-scale dependency.An HMT model can capture well the statistical properties of radar precipitation,where the wavelet coefficients in each sub-band are characterized as a Gaussian mixture model(GMM),and the wavelet coefficients from the coarse scale to fine scale are described using a multiscale Markov process.The state probabilities of the GMM are determined using the expectation maximization method,and other parameters,for instance,the variance decay parameters in the HMT model are learned and estimated from high-resolution ground radar reflectivity images.Using the prior model,the wavelet coefficients at finer scales are estimated using local Wiener filtering.The interpolation algorithm is validated using data from the precipitation radar onboard the Tropical Rainfall Measurement Mission satellite,and the reconstructed results are found to be able to enhance the spatial resolution while optimally reproducing the local extremes and gradients.

Analysis of dynamic stress intensity factors of thick-walled cylinder under internal impulsive pressure

Dynamic stress intensity factors are evaluated for thick-walled cylinder with a radial edge crack under internal impulsive pressure. Firstly, the equation for stress intensity factors under static uniform pressure is used as the reference case, and then the weight function for a thick-walled cylinder containing a radial edge crack can be worked out. Secondly, the dynamic stresses in uncracked thick-walled cylinders are solved under internal impulsive pressure by using mode shape function method. The solution consists of a quasi-static solution satisfying inhomogeneous boundary conditions and a dynamic solution satisfying homogeneous boundary condi- tions, and the history and distribution of dynamic stresses in thick-walled cylinders are derived in terms of Fourier-Bessel series. Finally, the dynamic stress intensity factor equations for thick-walled cylinder containing a radial edge crack sub- jected to internal impulsive pressure are given by dynamic weight function method. The finite element method is utilized to verify the results of numerical examples, showing the validity and feasibility of the proposed method.

The Application of Curriculum Ideological and Political Cases in the Teaching of Road Survey and Design

Ideological and political construction of curriculum is the key link to implement the fundamental task of moral education.Focusing on the training objectives of civil engineering professionals in the new era,combined with the teaching concepts of moral education and student-centered education,the teaching objectives for the course of road survey and design have been re-set.The implementation plan of ideological and political education has been put into practice by involving excellent engineering cases,stories of outstanding figures in this field,traffic accidents,design concepts and technological innovation to explore the methods of integrating ideological and political cases into curriculum teaching for a continuous improvement of the promotion of curriculum ideological and political education to the teaching quality of professional courses.

Influence of biological treatments on intestinal microbiota of psoriasis patients

To the Editor:Psoriasis is a common,chronic inflammatory skin disease occurring worldwide and presenting at any age.[1]Biologics are the most important therapeutic advances in psoriasis treatment.[2]With the development of 16S rRNA sequencing technology,the association between psoriasis and intestinal flora has been gradually revealed.Some bacteria secrete short-chain fatty acids(SCFAs)with anti-inflammatory properties,serving as active microbial metabolites that regulate the function of immune cells in the intestine and other tissues.[3]However,the impact of biological treatment on gut microbiota and related functional changes in psoriasis patients remains unclear.Our study aimed to explore the effects of biological treatments on the intestinal microbiota of psoriasis patients.